A super-hydrophobic and corrosion-resistant iron-based amorphous alloy coating and its preparation method

Abstract

The present invention discloses a method for constructing a super-hydrophobic surface of an iron-based amorphous alloy coating and significantly improving its corrosion resistance, and relates to the field of surface engineering technology. The method comprises: S1, obtaining an iron-based amorphous coating by HVAF technology, S2, chemical etching treatment of the coating surface, S3, crosslinking of nano-TiO2 particles with a perfluorodecyltriethylsilane solution, and S4, modification of the coating surface. The method has the following advantages: (1) the coating after spraying has a natural roughness suitable for manufacturing a super-hydrophobic surface; (2) the surface treatment process is simple, efficient, and low in cost; (3) the composite of nanoparticles and perfluorodecyltriethylsilane not only realizes the construction of a super-hydrophobic surface nanostructure and the reduction of surface energy, but also has the function of filling the pore defects generated by the amorphous coating during the preparation process; (4) the coating has good super-hydrophobicity and self-cleaning properties, and at the same time exhibits significantly outstanding corrosion resistance.

Description

Technical Field

[0001] The present invention relates to the technical field of surface engineering, and in particular to a super-hydrophobic and corrosion-resistant iron-based amorphous alloy coating and a preparation method thereof. Background Art

[0002] Iron-based amorphous alloys are considered among the most promising engineering materials due to their ultra-high hardness and strength, excellent wear resistance, and low material cost among various glass alloy systems. Their excellent corrosion resistance also makes them suitable candidates for surface protection of metal substrates in various aggressive environments, including marine and erosion-corrosion environments, boilers, gas turbines, and the nuclear industry.

[0003] The high corrosion resistance of iron-based amorphous alloys is primarily attributed to three factors: First, microstructural homogeneity. Amorphous alloys lack defects such as grain boundaries, secondary phases, precipitates, dislocations, and stacking faults. Furthermore, iron-based amorphous alloys possess the property of being a single-phase, homogeneous solid solution, ideally free of physical or chemical inhomogeneities. Therefore, iron-based amorphous alloys with sufficient amounts of corrosion-resistant elements exhibit remarkable corrosion resistance. Second, iron-based amorphous alloys are characterized by the presence of corrosion-resistant solute elements, which, in their reduced state, have high chemical stability and affinity for oxygen, and these elements tend to accumulate in the passive film. Third, the high reactivity of the iron-based amorphous structure accelerates the formation of the passive film in corrosive environments, thereby enhancing its protective capabilities. This high reactivity is caused by the metastable structure of the amorphous alloy, allowing the passive film to nucleate simultaneously at many active sites and then grow to connect and form a continuous protective film. Amorphous alloys typically possess high corrosion resistance, but the corrosion resistance of prepared amorphous alloy coatings is significantly reduced. This is primarily due to the introduction of structural defects during the coating preparation process: pores, crystalline phases, and oxidation. In some harsh corrosive media, these coating structural defects interact and interconnect, allowing the corrosive medium to penetrate the coating-substrate interface, causing severe corrosion of the substrate and ultimately leading to coating failure.

[0004] In recent years, inspired by biomimetics, super-hydrophobic surfaces with static water contact angles greater than 150° and rolling angles less than 10° have become a new technology for surface corrosion protection. By acting as a liquid barrier, they can alleviate the long-standing corrosion problems of metals and their alloys. Based on the natural micron-roughness and low surface energy of sprayed iron-based amorphous alloy coatings, the research and development of super-hydrophobic iron-based amorphous alloy coatings with high corrosion resistance has significant implications for both marine engineering and the military. Summary of the Invention

[0005] In response to the corrosion problem of key components of iron-based amorphous coating equipment in harsh corrosive environments, and in order to further improve the corrosion resistance of iron-based amorphous coatings, the present invention provides a super-hydrophobic and corrosion-resistant iron-based amorphous alloy coating and a preparation method thereof. This method not only achieves excellent super-hydrophobicity and self-cleaning properties, but also takes into account outstanding corrosion resistance. It has the advantages of simple surface treatment process, high efficiency and low cost.

[0006] To achieve the above object, the technical solutions adopted by the present invention are as follows:

[0007] A method for preparing a super-hydrophobic and corrosion-resistant iron-based amorphous alloy coating comprises the following steps:

[0008] (1) Preparation of iron-based amorphous coating:

[0009] The high velocity oxygen fuel (HVAF) spraying technology is used to spray multiple passes on the pretreated substrate surface to prepare an iron-based amorphous coating with micron-level roughness.

[0010] (2) Chemical etching treatment of coating surface:

[0011] The coating prepared in step (1) was etched in an acid-hydrogen peroxide mixed solution to activate the coating surface. After being taken out, the coating was ultrasonically treated in a pure alcohol solution for 10 minutes to remove the residual liquid on the surface and then vacuum dried.

[0012] (3) Crosslinking of nano-TiO2 and perfluorodecyltriethylsilane:

[0013] Nano-TiO2 particles and perfluorodecyltriethylsilane solution are mixed in proportion and cross-linked under ultrasonic action to obtain a hydrophobic polymer.

[0014] (4) Coating surface modification

[0015] The coating treated in step (2) is immersed in the hydrophobic polymer solution obtained in step (3), subjected to low-energy modification treatment by heating in a water bath, and finally dried in a vacuum drying oven to obtain a super-hydrophobic and corrosion-resistant iron-based amorphous coating.

[0016] Preferably, the HVAF supersonic flame spraying process in step (1) is to heat and melt an iron-based amorphous alloy powder with a particle size range of 18 to 53 μm and spray it onto the surface of the substrate or component, wherein kerosene is used as fuel, oxygen is used as a combustion aid, propane is used as fuel gas, compressed air is used as a combustion aid, and hydrogen and nitrogen are used to improve process flexibility. The spraying process parameters are: compressed air pressure 75 psi; combustion aid pressure 70 psi; propane flow rate: 130 SLPM; hydrogen flow rate: 30 SLPM; nitrogen flow rate: 30 SLPM; powder feed rate: 8 rpm; spray distance: 200 mm; cooling water flow rate: 15 L / min.

[0017] Preferably, the chemical etching reagent in step (2) is a mixture of 98 wt.% nitric acid, 30 wt.% hydrogen peroxide and deionized water (volume ratio ml: 5:2:15), the etching time is 5-15 minutes, and the etching is carried out in a static water environment.

[0018] Preferably, in step (3), the particle size of the nano-TiO2 particles is 30-50 nm, the concentration of the perfluorodecyltriethylsilane solution is 1 wt.%, (mixing 50 g of nano-TiO2 particles and 25 ml of perfluorodecyltriethylsilane solution), the crosslinking time is 1 h, and the crosslinking reaction temperature is 35°C.

[0019] Preferably, in step (4), the surface modification time of the coating is 90 minutes, the water bath temperature is 100° C., the vacuum drying temperature is 100° C., and the drying time is 1 hour.

[0020] The principle of the method described in the present invention is: by constructing a super-hydrophobic surface with good water repellency on the iron-based amorphous alloy coating, the corrosion resistance of the iron-based amorphous coating is greatly improved, the coating surface is activated by chemical etching, and the coating is immersed in a cross-linked solution of nanoparticles and perfluorodecyltriethylsilane. While constructing a super-hydrophobic micro-nano structure on the surface of the iron-based amorphous coating, the fluorinated nanoparticles can also fill the pores of the coating to act as a physical barrier. The synergistic effect of this micro-nano structure and physical barrier can significantly improve the corrosion resistance of the coating.

[0021] The beneficial effects of the present invention are as follows:

[0022] (1) The iron-based amorphous coating prepared by the high velocity oxygen flame spraying (HVAF) technology of the present invention has a natural roughness that constructs a super-hydrophobic surface.

[0023] (2) The super-hydrophobic iron-based amorphous coating constructed by the present invention not only constructs a super-hydrophobic micro-nano structure on the coating surface but also compensates for the pore defects generated during the coating preparation process by introducing nano-particles TiO2 and cross-linking with perfluorodecyltriethylsilane solution.

[0024] (3) The surface treatment process of the present invention is simple, efficient, low-cost and can be prepared on substrates with complex structures.

[0025] (4) The super-hydrophobic iron-based amorphous coating prepared by the present invention achieves a water contact angle of >150° and a rolling angle of <10°, has good super-hydrophobicity, and exhibits outstanding corrosion resistance. The passivation current density of the coating is reduced by three orders of magnitude in the corrosion resistance test. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] Figure 1The raw material powder image, coating morphology, and XRD and DSC images for determining the amorphous phase and content of the iron-based amorphous coating prepared in Example 1 of the present invention; wherein: (a) is the raw material powder image, (b) is the coating surface morphology image, (c) is the coating XRD image, and (d) is the coating DSC image.

[0027] Figure 2 This is a modification diagram of the iron-based amorphous superhydrophobic surface prepared in Example 1 of the present invention after etching; wherein: (a) is the hydrolysis of perfluorodecyltriethylsilane, (b) is the cross-linking effect of perfluorodecyltriethylsilane and nanoparticle TiO2, and (c) is the surface modification of the coating after immersion in the cross-linking mixture.

[0028] Figure 3 Graph showing the contact angles of the iron-based amorphous super-hydrophobic coating prepared in Example 1 of the present invention; wherein: (a) is the water contact angle, and (b) is the salt contact angle of 3.5% NaCl.

[0029] Figure 4 The surface morphology of the iron-based amorphous super-hydrophobic coating prepared in Example 1 of the present invention and the macroscopic water droplet image of the coating surface in the upper right corner; wherein: (a) is the original coating without any treatment, (b) is the surface morphology after etching, (c) is the surface morphology after etching and modification with perfluorodecyltriethylsilane, and (d) is the surface morphology after etching and modification by cross-linking of nanoparticles and perfluorodecyltriethylsilane.

[0030] Figure 5 Surface morphology and composition distribution of the iron-based amorphous super-hydrophobic coating prepared in Example 1 of the present invention; wherein: (a) is the surface morphology of the iron-based amorphous super-hydrophobic coating, (b) is a local enlarged view of (a), and (c) is the component surface distribution of (b).

[0031] Figure 6 This is a jet test of the iron-based amorphous super-hydrophobic coating prepared in Example 2 of the present invention.

[0032] Figure 7 This is a test of the electrochemical corrosion behavior of the iron-based amorphous super-hydrophobic coating prepared in Example 2 of the present invention. DETAILED DESCRIPTION

[0033] The present invention will be further described in detail below in conjunction with the accompanying drawings and Examples. The following examples are intended to facilitate understanding of the present invention and do not have any limiting effect on it. Without departing from the spirit and substance of the present invention, modifications and replacements made to the inventive method, steps or conditions all fall within the scope of the present invention. Unless otherwise specified, the technical means used in the examples are conventional means well known to those skilled in the art.

[0034] Example 1

[0035] A super-hydrophobic and corrosion-resistant iron-based amorphous alloy coating and a preparation method thereof, the method comprising the following steps:

[0036] (1) Obtaining iron-based amorphous coatings by high velocity oxygen fuel (HVAF) spraying technology

[0037] Using high velocity oxygen fuel (HVAF) spraying technology, a multi-pass iron-based amorphous coating with micron-scale roughness is deposited on a pretreated substrate. The process involves heating and melting an iron-based amorphous alloy powder with a particle size range of 18 to 53 μm and spraying it onto the substrate or component surface. Kerosene is used as the fuel, oxygen as the combustion aid, propane as the fuel gas, and compressed air as the combustion aid. Hydrogen and nitrogen are used to enhance process flexibility. Spraying parameters are: compressed air pressure of 75 psi; combustion aid pressure of 70 psi; propane flow rate of 130 SLPM; hydrogen flow rate of 30 SLPM; nitrogen flow rate of 30 SLPM; powder feed rate of 8 rpm; spray distance of 200 mm; cooling water flow rate of 15 L / min.

[0038] (2) Chemical etching treatment of coating surface

[0039] The prepared coating was etched in a chemical etching reagent acid-hydrogen peroxide mixed solution to activate the coating surface. The chemical etching reagent was a mixture of 98wt.% nitric acid, 30wt.% hydrogen peroxide and deionized water (volume ratio ml: 5:2:15). The etching time was 10min and the etching was carried out in a static water environment. After removal, the residual liquid on the surface was removed by ultrasonication in anhydrous ethanol solution for 10min and vacuum drying was performed.

[0040] (3) Crosslinking of nano-TiO2 and perfluorodecyltriethylsilane

[0041] Nano-TiO2 particles were mixed with a 1 wt.% perfluorodecyltriethylsilane solution (50 g of nano-TiO2 particles and 25 ml of the perfluorodecyltriethylsilane solution) and then cross-linked under ultrasound to produce a hydrophobic polymer. The nano-TiO2 particles had a diameter of 35 nm, the perfluorodecyltriethylsilane solution had a concentration of 1 wt.%, and the cross-linking time was 1 hour at 35°C.

[0042] (4) Coating surface modification

[0043] The treated coating (2) was immersed in the hydrophobic polymer solution (3), heated in a water bath for low-energy modification, and finally dried in a vacuum drying oven to obtain a super-hydrophobic, corrosion-resistant iron-based amorphous coating. The surface modification time of the coating was 90 minutes, the water bath temperature was 100°C, the vacuum drying temperature was 100°C, and the drying time was 1 hour.

[0044] Figure 1 (a) is the morphology of the iron-based amorphous powder under scanning electron microscopy. It can be seen that the powder is in a uniform spherical state with an average particle size of 30 μm. Figure 1 (b) is the iron-based amorphous coating after spraying, showing a natural micron roughness. Figure 1 (c) XRD patterns of the iron-based amorphous coating and strips. There is a broad diffuse diffraction peak between 2θ = 40° and 50°. The positions and shapes of the XRD peaks of the coating and strips are highly consistent, showing typical amorphous characteristics. Figure 1 (d) is the DSC spectrum of the iron-based amorphous coating. In order to quantify the content of amorphous in the iron-based amorphous layer, Figure 1 (d) The DSC heat flow diagram of the strip and coating samples is given. The amorphous phase fraction contained in the coating can be evaluated by the crystallization enthalpy (ΔH), that is, the ratio of the crystallization enthalpy ΔH of the coating and the strip sample in the DSC curve. The amorphous content of the coating is calculated to be 97.8%, which is almost completely amorphous.

[0045] A key factor in obtaining superhydrophobic surfaces is low surface energy modification. Figure 2 (a) Shows the hydrolysis of perfluorodecyltriethylsilane into the corresponding hydroxysilane. Since nanomaterials are rich in hydroxyl groups, the hydroxyl groups on the surface serve as anchor points to form covalent bonds with the hydroxysilane, which helps improve the surface grafting efficiency. Figure 2 (b) Nano-TiO2 and hydrolyzed hydroxysilane are cross-linked to form a hydrophobic polymer. Figure 2 (c) is a low-energy surface modification process of the coating. First, the hydrophobic polymer is ultrasonicated. Under the action of ultrasound, the nanoparticles are evenly dispersed. Then, the iron-based amorphous coating is immersed in the hydrophobic polymer and reacted in a water bath at 100°C for 90 minutes to form a super-hydrophobic iron-based amorphous coating.

[0046] Figure 3 The hydrophobic angle and salt repellent angle of super-hydrophobic coatings prepared by iron-based amorphous coatings under different surface treatments are expressed. Figure 3 Both (a) and (b) achieved superhydrophobic angles and supersalophobic angles of >150°, and the preparation of superhydrophobicity required three stages: etching, cross-linking of nanoparticles and perfluorodecyltriethylsilane, and surface modification.

[0047] Figure 4 The surface morphology of super-hydrophobic iron-based amorphous coating under different surface treatments. Figure 4 (a) is the original coating, the surface morphology is slightly convex and there are a few pores. Figure 4 (b) is the coating after etching. After acid etching and activation, a large number of etch pits are generated on the surface. Figure 4 (c) is the coating after etching and surface modification with perfluorodecyltriethylsilane, Figure 4(d) shows the coating after etching, cross-linking of nanoparticles with perfluorodecyltriethylsilane, and surface modification, with clusters of nanoparticles generated on the coating surface.

[0048] In order to verify the successful grafting of hydrophobic polymer, scanning electron microscopy (SEM) analysis was performed. Figure 5 (a) is the surface morphology of the super-hydrophobic iron-based amorphous coating. Figure 5 (b) is an enlarged view of (a). Figure 5 (c) is the surface distribution analysis of elements in (b). The surface distribution of elements shows that Ti and O elements indicate the presence of nano-TiO2 particles on the super-hydrophobic surface, and the presence of F element indicates that fluorinated silane that can reduce the surface energy is successfully grafted.

[0049] Example 2

[0050] A super-hydrophobic and corrosion-resistant iron-based amorphous alloy coating and a preparation method thereof, the method comprising the following steps:

[0051] (1) Obtaining iron-based amorphous coatings by high velocity oxygen fuel (HVAF) spraying technology

[0052] An iron-based amorphous coating with micron-scale roughness was deposited using high velocity oxygen fuel (HVAF) spraying technology in multiple passes on a pretreated substrate. Spraying parameters were: air pressure 75 psi; fuel gas pressure 70 psi; propane flow rate 130 SLPM; hydrogen flow rate 30 SLPM; nitrogen flow rate 30 SLPM; powder feed rate 8 rpm; spray distance 200 mm; and cooling water flow rate 15 L / min.

[0053] (2) Chemical etching treatment of coating surface

[0054] The prepared coating was etched in an acid-hydrogen peroxide mixed solution to activate the coating surface. The chemical etching reagent was selected from a mixture of 98wt.% nitric acid, 30wt.% hydrogen peroxide and deionized water (volume ratio ml: 5:2:15). The etching time was 15min. The etching was carried out in a static water environment. After removal, the residual liquid on the surface was removed by ultrasonication in anhydrous ethanol solution for 10min and vacuum drying was performed.

[0055] (3) Crosslinking of nano-TiO2 and perfluorodecyltriethylsilane

[0056] Nano-TiO2 particles were mixed with a 1 wt.% perfluorodecyltriethylsilane solution (50 g of nano-TiO2 particles and 25 ml of the perfluorodecyltriethylsilane solution) and then cross-linked under ultrasound to produce a hydrophobic polymer. The nano-TiO2 particles had a diameter of 40 nm, the perfluorodecyltriethylsilane solution had a concentration of 1 wt.%, and the cross-linking time was 1 hour at 35°C.

[0057] (4) Coating surface modification

[0058] The coating treated in (2) was immersed in the cross-linking solution (3), heated in a water bath for low-energy modification, and finally dried in a vacuum drying oven to obtain a super-hydrophobic, corrosion-resistant iron-based amorphous coating. The surface modification time of the coating was 90 minutes, the water bath temperature was 100°C, the vacuum drying temperature was 100°C, and the drying time was 1 hour.

[0059] Figure 6 This is a jet test of a super-hydrophobic iron-based amorphous coating. The surface of the coating is covered with nanopowder. Steps (1)-(9) show that as the water jet proceeds, it is found that the nanopowder on the surface of the coating disappears with the water flow, indicating that the prepared super-hydrophobic coating not only has good water repellency, but also has excellent self-cleaning properties.

[0060] Figure 7 To test the electrochemical corrosion behavior of the super-hydrophobic iron-based amorphous coating, the test environment was 3.5% NaCl solution. It was found that compared with the original coating, the self-corrosion potential of the super-hydrophobic iron-based amorphous coating was increased, while the self-corrosion current density was reduced and reached three orders of magnitude, which shows that the super-hydrophobic iron-based amorphous coating has significantly outstanding corrosion resistance.

Claims

1. A method for preparing a super-hydrophobic and corrosion-resistant iron-based amorphous alloy coating, characterized in that: The method comprises the following steps: (1) Preparation of iron-based amorphous coating: The high velocity oxygen fuel (HVAF) spraying technology is used to spray multiple times on the pretreated substrate surface to prepare an iron-based amorphous coating with micron-level roughness. (2) Chemical etching treatment of coating surface: The coating prepared in step (1) is etched in an acid-hydrogen peroxide mixed solution to activate the coating surface. After removal, the coating is ultrasonicated in anhydrous ethanol for 10 minutes to remove residual liquid on the surface and then vacuum dried. (3) Crosslinking of nano-TiO2 and perfluorodecyltriethylsilane: 50 g of nano-TiO2 particles were mixed with 25 ml of a 1 wt.% perfluorodecyltriethylsilane solution and then cross-linked under ultrasound to obtain a hydrophobic polymer solution; the nano-TiO2 particles had a particle size of 30-50 nm, the cross-linking time was 1 hour, and the cross-linking reaction temperature was 35°C; (4) Coating surface modification: The coating treated in step (2) is immersed in the hydrophobic polymer solution obtained in step (3), heated in a water bath for low-energy modification (surface modification), and then dried in a vacuum drying oven to obtain the super-hydrophobic and corrosion-resistant iron-based amorphous coating.

2. The method for preparing a super-hydrophobic and corrosion-resistant iron-based amorphous alloy coating according to claim 1, wherein: The high velocity oxygen flame spraying (HVAF) process in step (1) is to heat and melt an iron-based amorphous alloy powder with a particle size range of 18 to 53 μm and spray it onto the surface of a substrate or component, wherein kerosene is used as fuel, oxygen is used as a combustion aid, propane is used as fuel gas, compressed air is used as a combustion aid, and hydrogen and nitrogen are used to improve the flexibility of the process.

3. The method for preparing a super-hydrophobic and corrosion-resistant iron-based amorphous alloy coating according to claim 2, wherein: The HVAF process parameters of step (1) are: compressed air pressure 75 psi; combustion aid pressure 70 psi; propane flow rate: 130 SLPM; hydrogen flow rate: 30 SLPM; nitrogen flow rate: 30 SLPM; powder feeding rate: 8 rpm; spraying distance: 200 mm; cooling water flow rate: 15 L / min.

4. The method for preparing a super-hydrophobic and corrosion-resistant iron-based amorphous alloy coating according to claim 1, wherein: In step (2), the acid-hydrogen peroxide mixed solution is prepared by mixing 98 wt.% nitric acid, 30 wt.% hydrogen peroxide and deionized water in a volume ratio of 5:2:

15. The etching time is 5-15 minutes, and the etching is performed in a static water environment.

5. The method for preparing a super-hydrophobic and corrosion-resistant iron-based amorphous alloy coating according to claim 1, wherein: In step (4), the surface modification time of the coating in the water bath is 90 minutes, the water bath temperature is 100° C.; the vacuum drying temperature is 100° C., and the drying time is 1 hour.

6. A super-hydrophobic and corrosion-resistant iron-based amorphous alloy coating prepared by the method according to any one of claims 1 to 5.

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